Need to file a complaint with the service dept / extended warranty usage

I shop at micro center not because your prices are good but because you offer a 2-3 year warranty on products at +/-10% cost. This is really appealing to me as I don't want to wait 1-2 weeks on shipping from an online retailer if I have an issue. I was told by the sells rep that I could use this warranty to get a refund for any reason even if that reason was that I wasn't satisfied with the product after purchasing the warranty. In the past 5 years I've spent nearly $7,000 at your store with $400 of it being on extended warranties. I tried to return this card under the warranty because the primary display port worked intermittently with my 48" 4k monitor. I was told by the return / tech manager that they could not honor the warranty unless they could replicate the issue on their test bench. After testing the card for approx. 6 hours I was called and told that they could not replicate the issue and therefore would not honor the warranty. I pointed out that they were testing on a 17-19 inch monitor that was probably 1080p or 1440p and that there were huge differences in bandwidth usage between these devices, and that I had doubt that their software would document a drop in the display signal.

I was told that nevertheless they would not honor the warranty unless they could replicate the issue.

My question is: Why would I continue to shop at your store if you won't honor the warranty, which is the only thing I value?

This exchange wasted 5 hours of my Saturday off only to be told by the manager that my business and money was not worth the risk that I might be trying to "scam" them to get an upgraded card for only the cost of the warranty. I've never before tried to use a warranty claim, and the one time I do, I'm told tough luck. Very disappointing.